OBJECTIVE: To determine blood pressure distribution in schoolchildren and to derive population specific reference values appropriate for age, gender and height status. DESIGN: Cross sectional observational study. SETTING: Schools in Ernakulam district, Kerala, India, during 2005-06. METHODS: Stratified random cluster sampling method was used to select the children. Blood pressure and anthropometric data were collected from 20,263 students of 5-16 years age. Three readings of blood pressures of each child were taken by mercury sphygmomanometer and mean was taken for analysis. Blood pressure percentiles in relation to gender, age and height were estimated from a non-overweight population of 18,931 children using polynomial regression models. RESULTS: Children from study population have higher diastolic pressures for both sexes than international standard across all age groups. For systolic blood pressure, girls showed higher values than the international standard while for boys, the difference appears to be minimal. CONCLUSIONS: Blood pressure distribution in children from our study population demonstrates a different pattern in comparison to existing international reference. Higher blood pressure values in the study population are of considerable public health significance.